完整版自制的电火花穿孔机.docx

完整版自制的电火花穿孔机.docx

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完整版自制的电火花穿孔机

自制的电火花穿孔机

转贴的，我也回答不了具体总体。

感谢Zhang56网友提供的电路图。

电火花打小孔工具

摆轮是手表最重要部件,其上下两个轴尖因不停来回转动,在润滑不良情况下,很易磨损,一些老旧表特别是无防震功能的老怀表更是主要损坏件之一,

修复方法主要有:

1;更换整个摆轮~有原厂摆轮最好,但要注意其惯性距要一样,不然在调整走时快慢会有麻烦,最好是连游丝（整个震荡系统）一同更换~2;锡焊摆轴尖,早年有配件厂专生产一种轴尖,状如铆钉,先将旧轴适当磨短,然后将轴尖大头与摆轴锡焊接,但焊后很难达到同轴度要求,摆轮容易变色不是好办法~3;碰焊法;该法除要求焊接规范（压力,电流,时间）参数适当外,还有一大缺点,就是摆轴材质为炭素工具钢（相当于国内牌号T10A）由於含炭高,焊核因急剧冷却导致晶粒粗大,内应力增加,硬和碎都给后期修磨轴尖带来困难,该法在工业中只适用於低炭钢和镍合金如不锈纲等材质~4;只更换摆轴,此法更多缺点,由於摆轴除与摆轮配合,还要与游丝,下摆碟配合,在冲下旧摆轴和铆合新摆轴时,极易将摆轮弄变形,给后续调较带来更多问题,如果不是原厂配件,则更不宜采用~5;裁轴尖（广东人叫种车芯）方法是在已断轴尖根部打钻一小孔,压打入小钢丝,有时孔深不够还要焊锡以求牢固,优点是影响部位小,原断处下部凸台可作参考点,手艺好的师傅修后一般难以看出差别,缺点是需对摆轴退火,温度不足难钻孔,温度过高镀金摆轮将变色,钻头难磨,如果折断钻头则麻烦大了!

                            早年搞了个电火花打孔工具,上图与朋友交流

电源箱.jpg（36.55KB）

2009-6-2313:

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由于要打之孔很小,又是盲孔,不能用晶体管电路,只能用原始的RC电路,变压器功率为10W,输出电压40VDC,50VDC两挡,电容为金属化纸介电容,分0.01nF.0.22nF.0.47nF按要求组合

整机图.jpg（44.04KB）

2009-6-2313:

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工具1基座为后置导柱.周界为80x80模架,稳定性高可保证电极与摆轮工作时的垂直度和平行度要求

1;为电极头,用DQK电磁先导伐改装,线圈不变由220VAC供电,下部静铁芯长度比线圈长度一半再少1.5mm,中间有孔,压装于线圈导磁套内,上部动铁芯长度一样,但外径少1.5mm,端部装轴承,由0.15mm3J1恒弹性十字簧片固定于线圈外壳,下部也有轴承,同样由十字簧片固定干外壳,转轴由两轴承支承,下部为夹头,夹持紫铜电极,上端有小皮带轮,也是导电入口,再由220VAC/500转同步电机带动,整个电极头垂直装于上模扳,并与之绝缘,工作时电极边旋转边上下震动~

2;为旋转平台,内有轴承,外部装有煤油承液盘,摆轮平放干平台上,由一金属环通过三个簧片以重力轻压摆轮,使其导电,整个平台垂直装于下模板上,并与上电极同轴~

3;为电极修正器,装于下模扳,可作水平摆动和固定,旋转手轮可使电极座3前后移动~

4;为修正电极,实为一废手锯片,电蚀不平时可折下重磨~

5;为摆轮调正对中器,装于上模扳并与之绝缘,可水平摆动和固定,旋动手轮带动一刀口片,推动摆轮轴颈以调节同轴度~

6;为电容插座,实为IC测试座,不同电容量组合均装夹干此,此种布置不同于常规,如将电器元件均装于电箱内通过电线引出,则因电容量少,电压低而放电回路长,电阻大,放电电流下降不陡,火花效率就差,所以一定要将电容尽量靠近电极,减少回路电阻很关键,否则必失败~

7;为上模扳升降旋纽,旋纽下部有刻度,分为100格,每格0.01mm~

电路图：

使用方法

先将摆轮轴尖根部园弧处端面稍磨平,放置于平台上,由重力压块将摆轮轻压于平台,注意要导电良好~将紫铜电极装夹于电极头,尽量调少旋转偏摆,电箱右上角选择旋纽置于（修极）位,电容量选0.47nF,电压选高,左下边开关打向上,将电极修正器置于适当位置并固定,打上电源开关,此时电极又旋又震,转动各旋纽,用反烤法烧蚀电极,当直径接近要求时,改用精规范,以提高电极表面不平度,可降低打孔时电极损耗,见图三

电极修正后关电源,将电极升高,不使影响调中工作,移开电极修正器,将摆轮调中器5调到适当位并固定之,电箝右上角旋纽置于（调中）位,电压开关打向低端,旁边开关置於中间位置,调节旋纽7和摆轮调中器5上白色手轮,使刀口接近已断摆轴下凸台,电箱内通过分压器取得的2VDC在串入蜂鸣器后加于刀口与轴颈之间,一边慢漫转动平台2,通过听声音确定摆轴对中与否,（见下图）

对中后关电源,移开调中器,电箱右上角旋纽置於（打孔）位置,电压开关扳向下方（低）此时电压为40VDC,电容取0.022-0.22nF,频率取高点,规范取精,左下边第三个开关扳向下方（铭牌有误,应为震动）此时打孔电极只震动不旋转,调节旋纽7使电极接近摆轴,开始打孔,可通过电压表指示协助进级,无火花时指示最高,当电压低于25VDC时应停止进级,到指针上升后再进级~（图五）

在修电极和打孔时应用毛笔粘媒油湿润火花处,打孔直径大可用粗规范反之则取精规范,孔深可由旋纽7之刻度读取,由

于电极也损耗,实际深度约为刻度值0.6,一般孔深为孔径2.5-3倍即可~

  由于有可重置的规范,减少个人手艺因素,免去磨钻头,断钻头的麻烦,加上无需退火,摆轮不会变形变色,巳用十数次,不

失为较好的修复方法~一点个人心得,算是抛砖引玉~

RC电路图.JPG（36.33KB）

2009-11-116:

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修电极时先用粗规准,40V,0.22-0.47微法,精修电极时用30V,0.01-0.047微法,打孔时只用精规准,孔径大电容取大,反之取小.电容器安装尽量靠近电极和工件处,以减少放电回路的电阻!

AMini-EDMSystem

Overview

IbuiltasmallEDMsystem,primarilyforburningoutbroken-offtapsinaluminumparts.But,nowthatIseehoweasilyitworks,Icanseemanyotherthingsthatitcouldbeusedfor.Ibuiltthiswholesystemoveraweekend,entirelyoutofpartsIhadlayingaround.（Idohavealotofpieces,bothelectronicandmechanical.）

Electrode

TheelectrodeImadeupconsistedofapieceof.060brazingwiresolderedintothesocketofan8-32socket-headcapscrew.IthreadedthisintoanylonspacerthatIhappenedtohave,thatalreadyhadan8-32threadedholeinit.Iputthespacerintothedrillchuckonmymill.Thenylonspaceristheinsulatorthatpreventstheelectrodefromgroundingouttothechuck,andtherestofthemillingmachine.Iconnectedthepowersupplytotheelectrodebywayofasoftstrandedwire,sothatthewirewouldn'tdeflectthebrazingrod.Theendofthewirewasstrippedbackaboutoneinch,andthewirestrandswerelooselywrappedaroundthebrazingrod.Thismadearemarkablygoodelectricalcontact,whileallowingthebrazingrodtoturnfreely.Icouldputjustaslightbendintherodsothatitwouldmakeaveryslight（ie..010"）orbitifthespindlewererotated.Thisseemedtogetthebestmetalremovalanddepthprogressbeforetheholegotfilledwithremovedmetalandshortedout.

AviewoftheEDMelectrodeassemblyinaJacob'schuck.

PowerSupply

ThepowersupplyIthrewtogetherwasquitesimple.Avariac（variableautotransformer）isusedtoadjustoutputvoltage.A200Wattvariac（1-2Ampsat110V）isquiteadequate.Astep-downtransformer,whichprovidesisolation,isthenextcomponent.TheoneIusedwascenter-tapped,allowingtheuseof2rectifiers.Ifyourchoiceoftransformerdoesnothavethecentertap,orthevoltageistoolowwhenusingit,youcoulduseabridgerectifieronthetwoouterconnectionsofthesecondarytogethighervoltage.AfiltercapacitorprovidessmoothingoftheDCvoltageproduced.Aresistorallowstheelectrodetoshorttotheworkwithoutblowingfuses,andalsomoderatestheflowofcurrentfromtherawDCsupplytotheEDMcapacitorandelectrode.ChoosearesistancethatwillcauseashortcircuitcurrentatleasttwicethedesiredEDMcurrentattheselectedvoltage.Then,makesurethewattageissufficienttopreventtheresistorburningupduringafewsecondsofshortcircuit.WiththeDCsupplysetto30Volts,ashortwoulddrawapproximately1Amp,andsinceP=I^^2*R,thatisabout30W,usinga30OhmResistor.TheammetershowscurrentintotheEDMcapacitor.TheEDMcapacitordeliversshortburstsofveryhighcurrentwhenevertheinsulatingfilmoftheEDMfluidgetsverythinbetweentheelectrodeandworkpiece.

EDMFluid

Nothavingdistilledwateraround,Itriedtapwater.Itwasboiledawayveryquicklybyelectrolysis,anddidn'tdomuchgoodevenwhenitwasthere（perhapsallthatbubblinggotinthewayoftheEDMprocess）.Ithentriedthenearestthingathand,whichwas"Alum-Tap",alight,cleartappingfluidforaluminum.ItmustbeprettyclosetoEDMfluid,becauseitworkedsowell!

ItlastedalongtimebeforebeingspatteredawaybythegasesgeneratedbytheEDMaction.Mostofthetime,Ionlyhadtoaddafewdropsbeforetheholebecamefilledwithremovedmetal.

Operation

ThewayIsetthisupwasprettymuchbytrialanderror.But,herearemysettings:

Isetthepowersupplyfor30Volts.Thisseemedtogiveaverystrongdischargeactionwithoutproducingtoomuchgasorheat.IloweredtheelectrodewithmyNCcontrol'sjogbuttonsuntilIgotelectrodecontact（indicatedbyabout1Ampcurrentsuddenlyappearingontheammeter）.Ithenraisedtheelectrodewithaveryslowjoguntilthecurrentdroppedtozero.Ithenenteredamanualcommandtoadvancetheelectrodeatarateofabout.010"/minute,andafterafewseconds,theammeterwouldshowacurrentof1/4to1/2amp.Iwouldmodulatethefeedratewiththefeedrateoverridecontrols,attemptingtokeepthecurrentwithintheselimits.Bybendingtheelectrodejustatinybit,andrunningthemill'sspindleattheslowestspeed（80RPM）,IcouldgetanydiameterholeIwanted.Isetittojustkeepatinybitoftheflankofthetap,buttoburnouttheentireweb（centralportion）ofthetap.Thisallowedmetopicktheremainingpartofthetap'scuttingedgeoutofthealuminumeasilywithafineneedlewhentheEDMelectrodehadcutallthewaythrough.ProgressallthewaythroughwasevidentwhenthetoolwasstilladvancingwithnoEDMcurrent.

SinceIdidn'thaveameansofprovidingaflowofEDMfluidthroughsuchasmallelectrode,Ihadtopulltheelectrodeupevery.025"orso,wipeoutthecontaminatedfluidwithapapertowel,andthendripafewdropsoftheAlum-Tapintothehole.